[PATCH AUTOSEL 5.15 20/23] fbdev: fb_pm2fb: Avoid potential divide by zero error

[PATCH AUTOSEL 5.15 20/23] fbdev: fb_pm2fb: Avoid potential divide by zero error

[Sasha Levin]

From: Letu Ren <fantasquex@gmail.com>

[ Upstream commit 19f953e7435644b81332dd632ba1b2d80b1e37af ]

In `do_fb_ioctl()` of fbmem.c, if cmd is FBIOPUT_VSCREENINFO, var will be
copied from user, then go through `fb_set_var()` and
`info->fbops->fb_check_var()` which could may be `pm2fb_check_var()`.
Along the path, `var->pixclock` won't be modified. This function checks
whether reciprocal of `var->pixclock` is too high. If `var->pixclock` is
zero, there will be a divide by zero error. So, it is necessary to check
whether denominator is zero to avoid crash. As this bug is found by
Syzkaller, logs are listed below.

divide error in pm2fb_check_var
Call Trace:
 <TASK>
 fb_set_var+0x367/0xeb0 drivers/video/fbdev/core/fbmem.c:1015
 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110
 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189

Reported-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Letu Ren <fantasquex@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/pm2fb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/video/fbdev/pm2fb.c b/drivers/video/fbdev/pm2fb.c
index c68725eebee3b..cbcf112c88d30 100644
--- a/drivers/video/fbdev/pm2fb.c
+++ b/drivers/video/fbdev/pm2fb.c
@@ -617,6 +617,11 @@ static int pm2fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 		return -EINVAL;
 	}
 
+	if (!var->pixclock) {
+		DPRINTK("pixclock is zero\n");
+		return -EINVAL;
+	}
+
 	if (PICOS2KHZ(var->pixclock) > PM2_MAX_PIXCLOCK) {
 		DPRINTK("pixclock too high (%ldKHz)\n",
 			PICOS2KHZ(var->pixclock));
-- 
2.35.1

[PATCH AUTOSEL 5.15 21/23] fbdev: fbcon: Destroy mutex on freeing struct fb_info

[Sasha Levin]

From: Shigeru Yoshida <syoshida@redhat.com>

[ Upstream commit 58559dfc1ebba2ae0c7627dc8f8991ae1984c6e3 ]

It's needed to destroy bl_curve_mutex on freeing struct fb_info since
the mutex is embedded in the structure and initialized when it's
allocated.

Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/core/fbsysfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c
index ce699396d6bad..09ee27e7fc25f 100644
--- a/drivers/video/fbdev/core/fbsysfs.c
+++ b/drivers/video/fbdev/core/fbsysfs.c
@@ -84,6 +84,10 @@ void framebuffer_release(struct fb_info *info)
 	if (WARN_ON(refcount_read(&info->count)))
 		return;
 
+#if IS_ENABLED(CONFIG_FB_BACKLIGHT)
+	mutex_destroy(&info->bl_curve_mutex);
+#endif
+
 	kfree(info->apertures);
 	kfree(info);
 }
-- 
2.35.1

[PATCH AUTOSEL 5.15 22/23] fbdev: chipsfb: Add missing pci_disable_device() in chipsfb_pci_init()

[Sasha Levin]

From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 07c55c9803dea748d17a054000cbf1913ce06399 ]

Add missing pci_disable_device() in error path in chipsfb_pci_init().

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/chipsfb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/video/fbdev/chipsfb.c b/drivers/video/fbdev/chipsfb.c
index 393894af26f84..2b00a9d554fc0 100644
--- a/drivers/video/fbdev/chipsfb.c
+++ b/drivers/video/fbdev/chipsfb.c
@@ -430,6 +430,7 @@ static int chipsfb_pci_init(struct pci_dev *dp, const struct pci_device_id *ent)
  err_release_fb:
 	framebuffer_release(p);
  err_disable:
+	pci_disable_device(dp);
  err_out:
 	return rc;
 }
-- 
2.35.1